In some plumbing applications, it is necessary to transport hot and cold water separately from the respective hot and cold water supplies to an outlet, for example a tap, or other device having a mixer. Conventionally, the hot and cold water is transported by two separate pipes. However, in some cases, for example the water supply system of a boat or caravan, it is considered to be unsightly and cumbersome to provide two separate water pipes for this purpose.
It would be desirable to mitigate this problem.